The present invention generally relates to control of temperature of a flow of gas. More particular, the invention relates to control of such temperature in an environmental control system (ECS) of an aircraft.
In conventional aircraft ECS, engine bleed air may be used as an air source. Temperature control of the bleed air entering the ECS may be achieved by passing the bleed air through a heat exchanger that may be cooled by ram air. When ram air is introduced into an aircraft there may be a resultant increase in drag and fuel consumption. It is known that decreasing the amount of introduced ram air may increase aircraft efficiency. However, at low ram flows, accurate control of ECS temperature may be difficult to maintain when variations in bleed air temperature may occur.
As can be seen, there is a need to provide a system for accurately controlling ECS temperature during variations of temperature of bleed air emerging from an engine of an aircraft while minimizing ram air flow.